--[[
Made by DasEtwas
All rights reserved
]]--

-- global variables --

airDensity = 2.75
updateSleep = 80
maxAcceleration = 100 -- m/s² max acceleration
movementSleep = 10 -- how many ticks it takes for previously completely still wings to activate when velocity:length() > sleepVel
sleepVel = 0.5 -- m/s

-- utils --

function vecString(vec)
	return "["..tostring(math.floor((sm.vec3.getX(vec) * 1000) + 0.5) / 1000)..",".. tostring(math.floor((sm.vec3.getY(vec) * 1000) + 0.5) / 1000)..",".. tostring(math.floor((sm.vec3.getZ(vec) * 1000) + 0.5) / 1000).."]"
end

function form(num)
	return math.floor((num * 100) + 0.5) / 100
end

function sign(num)
	if num < 0 then
		return -1
	elseif num > 0 then
		return 1
	else
		return 0
	end
end

function equals(vec1, vec2)
	return sm.vec3.getX(vec1) == sm.vec3.getX(vec2) and sm.vec3.getY(vec1) == sm.vec3.getY(vec2) and sm.vec3.getZ(vec1) == sm.vec3.getZ(vec2)
end

function doAirfoilStuff( self, timeStep )
	-- check if lastPosition was set AND
	-- check if after taking the creation from the lift the shape's worldpos isnt wrong AND
	-- check if something was built onto the creation, which would screw up the shape's position

	if self.lastPosition then
		local currentPos = sm.shape.getWorldPosition(self.shape)

		if equals(currentPos, self.lastBodyPos) or (self.parentBodyMass ~= sm.body.getMass(self.shape:getBody())) then
			self.enabled = -updateSleep
		end

		--print("currentPos: " .. vecString(currentPos) .. ", lastBodyPos: " .. vecString(self.lastBodyPos) .. ", enabled: " .. self.enabled)

		local globalVel = (currentPos - self.lastPosition) / timeStep
		local globalVelL = globalVel:length()

		if (globalVelL < sleepVel) then
			self.sleep = movementSleep
		elseif self.sleep > 0 then
			self.sleep = self.sleep - 1
		end

		local acceleration = globalVelL

		if self.lastVelocity then
			acceleration = (globalVelL - self.lastVelocity) / timeStep
		end

		self.lastVelocity = globalVelL

		if self.enabled >= 0 and self.sleep == 0 then
			if math.abs(acceleration) < maxAcceleration then
				--print("lastPos: " .. vecString(self.lastPosition) .. ", currentPos: " .. vecString(sm.shape.getWorldPosition(self.shape)))
				--print("parent body pos: " .. vecString(sm.body.getPosition(self.shape:getBody())))

				local localX = sm.shape.getRight(self.shape)
				local localY = sm.shape.getUp(self.shape)
				local localZ = localX:cross(localY) -- normal vector
					self.normalVel = globalVel:dot(localZ)
				self.lift = airDensity * self.normalVel * self.normalVel * 0.5 * self.area * sign(self.normalVel)

				--print("mass: " .. tostring(sm.body.getMass(self.shape:getBody())))
				--print("velocity: " .. vecString(globalVel) .. ", enabled: " .. tostring(self.enabled))

				sm.physics.applyImpulse(self.shape, sm.vec3.new(0, self.lift, 0)) -- minus for other direction than velocity
			else
				print("too much acceleration: " .. tostring(form(acceleration)))
				--print("globalVelL: " .. tostring(form(globalVelL)))
			end
			--print("acceleration: " .. tostring(form(acceleration)))
		else
			self.enabled = self.enabled + 1
		end

	end

	self.lastBodyPos = sm.body.getPosition(self.shape:getBody())
	self.lastPosition = sm.shape.getWorldPosition(self.shape)
	self.parentBodyMass = sm.body.getMass(self.shape:getBody())
end

-- Airfoil1 --

Airfoil1 = class( nil )
Airfoil1.area = 1 -- m², in this case 4 * 4 blocks / 16 (conversion unit)
Airfoil1.enabled = -updateSleep -- prevent jitter from false lastPosition
Airfoil1.sleep = movementSleep

function Airfoil1.server_onCreate( self )
	self:server_init()
end

function Airfoil1.server_init( self )
	self.enabled = -updateSleep
end

function Airfoil1.server_onRefresh( self )
	self:server_init()
end

function Airfoil1.server_onFixedUpdate( self, timeStep )
	doAirfoilStuff(self, timeStep)
end

-- Airfoil2 --

Airfoil2 = class( nil )
Airfoil2.area = 0.25 -- m², in this case 4 * 4 blocks / 16 (conversion unit)
Airfoil2.enabled = -updateSleep -- prevent jitter from false lastPosition
Airfoil2.sleep = movementSleep

function Airfoil2.server_onCreate( self )
	self:server_init()
end

function Airfoil2.server_init( self )
	self.enabled = -updateSleep
end

function Airfoil2.server_onRefresh( self )
	self:server_init()
end

function Airfoil2.server_onFixedUpdate( self, timeStep )
	doAirfoilStuff(self, timeStep)
end

-- end of script --